Attack mode on at all times
Press Select during game play, then hold L1 and press Circle, Circle, Circle, Circle, X, Circle, Circle, Circle or Circle(4), X, Circle(4).

Chapter 3: Pearls
If you attack a puffer fish, many pearls will come out.

Chapter 9: Staying hidden
When you must sneak around the fish with lights on their heads or the ones with torches, there are some tables with cloths on them that you can go under without being detected.

Complete dance mode easier
Press X + Circle + Triangle + Square on each arrow. It will be counted as the arrow that is pointing to, even the doubles.

Replace all Pearls with Fish King coins
Press Select during game play on any level with Pearls, then hold L1 press Circle, X, Circle(3), X, Circle(2).

Replace all Pearls with Fish King coins
At any level where you can obtain pearls, press "Select" to show the controller guide, then hold L1 and enter: Circle, Square, Circle, Circle, Circle, Square, Circle, Circle.